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Menthol cold
The back pages Almost the last word Should we build wind farms or are they not worth the energy?
Galactic traveller My wife told me I should get out more. I replied that I am just about to celebrate my 66th free trip around the sun. Can anyone tell me how far I have travelled in our galaxy during that time?
Menthol cold Why do we experience a cold sensation in our mouth or nose when eating or inhaling menthol?
Herman D’Hondt Sydney, Australia The answer depends on what motions you include. The speed of the solar system around the galactic centre is about 230 kilometres per second. If you only include that, then you travel 7.26 billion kilometres per year, or 479 billion kilometres overall. However, we should also add the distance Earth has travelled around the sun and the distance your London home has travelled around Earth (at a speed of about 0.465 kilometres per second). These are much smaller amounts, but combined they add almost 63 billion kilometres to the total. Mike Follows Sutton Coldfield, West Midlands, UK The solar system sits some 26,500 light years from the galactic centre, about halfway along a spiral arm. We orbit the centre of the Milky Way about once every 240 million years. However, the universe has been expanding ever since the big bang, about 13.8 billion years ago. All galaxies are moving away from each other at a speed proportional to the distance that separates them. We can’t measure our speed relative to our starting point because the universe has no centre or edge. If there were nothing to disturb this motion, we would be stationary relative to the radiation left over from the 54 | New Scientist | 20 July 2019
THOMAS EBERT/PLAINPICTURE
Emma Eales Edinburgh, UK Earth moves at about 30 kilometres per second around the sun. If you count this as your own journey, you will have travelled about 62 billion kilometres in 66 Earth years.
This week’s new questions Wind economics What is the carbon payback period for a large wind farm, taking into account the energy and resources used for materials, manufacture and the construction of supporting infrastructure? If it is long, say 30 years, are they worth it? John Oxborrow, Coniston, Cumbria, UK Seven litres a day How does water hydrate us? If we drink a lot of it we only pass it as excess waste. Stefan Badham, Portsmouth, Hampshire, UK
big bang, the cosmic microwave background radiation. However, we are careering towards the Leo and Virgo constellations, pulled there at more than 600 kilometres per second by a group of galaxies dubbed the Great Attractor. This is nearly three times the speed at which we orbit the centre of the Milky Way. When we celebrate anniversaries, we really have moved on and we each have an absolutely unique trajectory on the fabric of space-time. Hillary J. Shaw Newport, Shropshire, UK Though you will have travelled about 62.5 billion kilometres around the sun in 66 years, it is a tiny distance in stellar terms: less than 1 per cent of a light year, or around 0.2 per cent of the distance from the sun to the nearest other star. If you want to “get out more” in stellar terms, consider inventing an antimatter drive that can take you up to 99.9 per cent of
light speed (and decelerate again). The resulting time dilation will enable you to tour much of the galaxy within your lifetime. But do take your wife with you, as when you return to Earth it will be many tens of thousands of years later. David Roffey London, UK Movement through space is a big problem for time travel. Assuming you can get past the trivial bit of transporting yourself 66 years into the past, you would then be trillions of kilometres from the spot on the planet that you started from. You would probably end up in a galactic void, which wouldn’t be good, and you would also have a small but non-zero chance of ending up in the gravity well of a star – even less good.
Steve Gisselbrecht Boston, Massachusetts, US We feel the cold sensation for essentially the same reason we get a burning feeling when we eat capsaicin, the “hot” in chillies. We have evolved nerve cells that sense heat, which help us know what not to touch, and they use proteins in their membranes that change shape in response to temperature. Menthol binds to the cold receptor protein and activates it in the same way cold would, just as capsaicin binds to and activates the hot receptor protein. Since our experience of cold is our brain receiving the message that these neurons have been activated, the feeling from menthol is identical to the feeling of actual cold. Plants that could make animals think they were too hot or cold to eat were less likely to be eaten, so there was evolutionary pressure to make such chemicals. David Cox CSIRO Health and Biosecurity Adelaide, Australia We sense “cooling” menthol with our trigeminal nerve, found in the oral and nasal cavity. This nerve also senses pungency and heat from foods like chillies and the “tingle” of carbonated drinks. The trigeminal nerve transmits pain, tactile and thermal sensations. It is the latter that gives menthol’s cooling feeling. But menthol is complex and can also be sensed as warming and aromatic depending on the conditions and concentration. ❚
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Email us at [email protected] Questions should be about everyday science phenomena Full terms and conditions at newscientist.com/lw-terms
Galactic traveller My wife told me I should get out more. I replied that I am just about to celebrate my 66th free trip around the sun. Can anyone tell me how far I have travelled in our galaxy during that time?
Menthol cold Why do we experience a cold sensation in our mouth or nose when eating or inhaling menthol?
Herman D’Hondt Sydney, Australia The answer depends on what motions you include. The speed of the solar system around the galactic centre is about 230 kilometres per second. If you only include that, then you travel 7.26 billion kilometres per year, or 479 billion kilometres overall. However, we should also add the distance Earth has travelled around the sun and the distance your London home has travelled around Earth (at a speed of about 0.465 kilometres per second). These are much smaller amounts, but combined they add almost 63 billion kilometres to the total. Mike Follows Sutton Coldfield, West Midlands, UK The solar system sits some 26,500 light years from the galactic centre, about halfway along a spiral arm. We orbit the centre of the Milky Way about once every 240 million years. However, the universe has been expanding ever since the big bang, about 13.8 billion years ago. All galaxies are moving away from each other at a speed proportional to the distance that separates them. We can’t measure our speed relative to our starting point because the universe has no centre or edge. If there were nothing to disturb this motion, we would be stationary relative to the radiation left over from the 54 | New Scientist | 20 July 2019
THOMAS EBERT/PLAINPICTURE
Emma Eales Edinburgh, UK Earth moves at about 30 kilometres per second around the sun. If you count this as your own journey, you will have travelled about 62 billion kilometres in 66 Earth years.
This week’s new questions Wind economics What is the carbon payback period for a large wind farm, taking into account the energy and resources used for materials, manufacture and the construction of supporting infrastructure? If it is long, say 30 years, are they worth it? John Oxborrow, Coniston, Cumbria, UK Seven litres a day How does water hydrate us? If we drink a lot of it we only pass it as excess waste. Stefan Badham, Portsmouth, Hampshire, UK
big bang, the cosmic microwave background radiation. However, we are careering towards the Leo and Virgo constellations, pulled there at more than 600 kilometres per second by a group of galaxies dubbed the Great Attractor. This is nearly three times the speed at which we orbit the centre of the Milky Way. When we celebrate anniversaries, we really have moved on and we each have an absolutely unique trajectory on the fabric of space-time. Hillary J. Shaw Newport, Shropshire, UK Though you will have travelled about 62.5 billion kilometres around the sun in 66 years, it is a tiny distance in stellar terms: less than 1 per cent of a light year, or around 0.2 per cent of the distance from the sun to the nearest other star. If you want to “get out more” in stellar terms, consider inventing an antimatter drive that can take you up to 99.9 per cent of
light speed (and decelerate again). The resulting time dilation will enable you to tour much of the galaxy within your lifetime. But do take your wife with you, as when you return to Earth it will be many tens of thousands of years later. David Roffey London, UK Movement through space is a big problem for time travel. Assuming you can get past the trivial bit of transporting yourself 66 years into the past, you would then be trillions of kilometres from the spot on the planet that you started from. You would probably end up in a galactic void, which wouldn’t be good, and you would also have a small but non-zero chance of ending up in the gravity well of a star – even less good.
Steve Gisselbrecht Boston, Massachusetts, US We feel the cold sensation for essentially the same reason we get a burning feeling when we eat capsaicin, the “hot” in chillies. We have evolved nerve cells that sense heat, which help us know what not to touch, and they use proteins in their membranes that change shape in response to temperature. Menthol binds to the cold receptor protein and activates it in the same way cold would, just as capsaicin binds to and activates the hot receptor protein. Since our experience of cold is our brain receiving the message that these neurons have been activated, the feeling from menthol is identical to the feeling of actual cold. Plants that could make animals think they were too hot or cold to eat were less likely to be eaten, so there was evolutionary pressure to make such chemicals. David Cox CSIRO Health and Biosecurity Adelaide, Australia We sense “cooling” menthol with our trigeminal nerve, found in the oral and nasal cavity. This nerve also senses pungency and heat from foods like chillies and the “tingle” of carbonated drinks. The trigeminal nerve transmits pain, tactile and thermal sensations. It is the latter that gives menthol’s cooling feeling. But menthol is complex and can also be sensed as warming and aromatic depending on the conditions and concentration. ❚
Want to send us a question or answer?
Email us at [email protected] Questions should be about everyday science phenomena Full terms and conditions at newscientist.com/lw-terms